Implement extend resource create a new object with added property

[czerwinskilukasz1]

While we have a resource for setting a value in an array (set resource), I think we don't have such for objects.

It is up to discussion whether a new resource should be created or rather set should be extended to work for objects.

[czerwinskilukasz1]

@mhagmajer , any thoughts?

[mhagmajer]

Because of data mutability we need to support extend for objects.

let a = { firstName: 'John' }
let b = extend(a, { lastName: 'Smith' }

should return { firstName: 'John', lastName: 'Smith' }

[czerwinskilukasz1]

@mhagmajer , would extend also change a value of an existing key?
E.g.:

let a = { firstName: 'John' }
a = extend(a, { firstName: 'Bill' }

[mhagmajer]

@czerwinskilukasz1

let a = { firstName: 'John' } // object X
a = extend(a, { firstName: 'Bill' } // object Y

Object X is going to stay the same no matter what you do. Object Y will be creating by extending object X which will overwrite its only property. Variable a is like a pointer. It can change what it points to because it is declared with let. It initially points to object X and then it points to object Y. Object X and object Y are immutable.

[czerwinskilukasz1]

Yes, I know. That's why I wrote 'change' in italics. Anyways, you answered my question: yes, extend will also work on a key that is already defined. So using extend could be a workaround for updating a value in a map.
Anyway, don't we need a set resource for maps?